Tory proposals to introduce a "zero tolerance" policy on drug offending have been condemned by police, drug charities and human rights groups.

Shadow home secretary Ann Widdecombe unveiled the plan, which would mean major changes in the way police deal with drug offenders, at the party conference in Bournemouth.

Under the proposals, anyone caught in possession of any quantity of any illegal drug, no matter how small, would face a minimum �100 fine.

It is a step backwards that will further criminalise young, otherwise law-abiding citizens Mike Goodman, Release

Drugs found in the bloodstream would count as possession and drivers would also face automatic disqualification for drug abuse at the wheel.

"We would not support this proposal," said Peter Williams, national secretary of the Police Superintendents' Association (PSA).

"The policy is not to punish people for possession of drugs, but to try to divert them from drugs.

"We support the present national strategy involving drug action teams, which have a very positive effect."

'Counter-productive'

While Fred Broughton, chairman of the Police Federation, welcomed "this unambiguous signal that drug taking is illegal", he said the practical policing implications would need to be examined.

Mike Goodman, director of national drug charity Release, said the Tory plan was bitterly disappointing.

"This proposal is wrong in principle and counter-productive in practice," he said.

"It is a step backwards that will further criminalise young, otherwise law-abiding citizens. The demonisation of cannabis users is simply not justified.

This policy is likely to increase criminal activity rather than reduce it Paul Cavadino, Nacro

"This proposal is more likely to bring our drugs laws into disrepute and undermine the progress that has been made in recent years in dealing with the genuinely dangerous drugs and improved treatment facilities for those who do have problems."

According to the latest published figures from the British Crime Survey, a quarter of the adult population has tried cannabis at some point.

Among 16 to 29-year-olds, this figure is 42%.

Convictions for cannabis possession have increased dramatically in the past decade.

According to the most recent figures, in 1998, 97,249 people were cautioned, fined or found guilty of possessing cannabis, nearly four times the level of 10 years before.

'Heavy-handed'

Paul Cavadino, of the National Association for the Care and Resettlement of Offenders (Nacro), said the proposals would do nothing for public safety.

"This heavy handed approach will create headaches for the police and bring the law into disrepute in the eyes of many otherwise law-abiding young people.

"A criminal record makes it harder to get a job. In view of the links between unemployment and crime, this policy is likely to increase criminal activity rather than reduce it."

The Human rights group Liberty described the proposals as a waste of police resources.

Dragging thousands of adults through the criminal justice system is a waste of police resources John Wadham, Liberty

Director John Wadham said: "Now is not the time to step up the penalties against drug users.

"Possession of small amounts of drugs should be decriminalised."

Home Office minister Charles Clarke told the BBC that the key issue in the fight against drugs was how to "ensure that serious drug abuse is dealt with through the criminal justice system".

"I think that is the real area where we have to focus, rather than a kind of PR stunt for the Tory party conference."

Officials estimate the Tory proposals would result in about 50,000 fixed penalty notices issued a year.